Characterization of the nature of an adrenal mass in a patient with known primary neoplasm in another organ is crucial to further clinical management. We intend to evaluate the feasibility of non-invasively and reliably differentiating between malignant and benign adrenal masses in 20 patients with known cancer using FDG-PET. The results of FDG-PET imaging will be compared with histopathology of biopsied or resected adrenal masses using ROC analysis.